Take a look through the "Pictures of your Rig
" thread. As far as I'm concerned any money spent on fancy boxes and desks is money not spent on GPU cards - and hence, wasted.
That assumes everyone has the same values and purpose. The guys running 42 cards from one rig in their mom's basement with 6 different fans from homedepot because they're 17 years old and don't know dick about distributed computing or clusters, well those are one type of miner. There are others that approach it professionally and have experience in datacenters and HPC/clustering - those are the guys that don't consider infrastructure a waste of money.
Cost is relative. Personally I don't mind dropping several hundred on a managed switch for my rack because I can watch port statistics and have multiple VLANs, but then there are other miners that cobble together a switch and router form a yard sale. It all depends on what you want out of your infrastructure and how much you are willing to invest in quality.
Putting all your money into GPUs is one thing but spending it all at the expense of having a stable and reliable infrastructure is stupid.